W32.Areses.H@mm is a mass-mailing worm that opens a back door on the compromised computer and may download files.

When W32.Areses.H@mm is executed, it performs the following actions:


Copies itself as the following file:

%Windir%\csrss.exe

Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.


Adds the value:

"Debugger" = "[PATH TO WORM]"

to the registry subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe


Adds the value:

"Application" = "[VARIABLE DWORD VALUE]"

to the registry subkey:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Devices


Deletes the value:

"BootExecute" = "autocheck autochk *"

from the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet\Control\Session Manager


Attempts to inject its code into the svchost.exe and sevices.exe processes.


Checks for the presence of the 127.0.0.1 string in the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
\Interface\[INTERFACE CLSID]\"NameServer"

Note: If the above value is found, it stops the mass-mailing routine.


Creates the following archive that contains a copy of itself:

%Temp%\message.zip

Note: %Temp% is a variable that refers to the Windows temporary folder. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).


Gathers email addressess from files with the following extensions:


.adb
.asp
.cfg
.cgi
.dbx
.dhtm
.eml
.htm
.html
.jsp
.mbx
.mdx
.mht
.mmf
.msg
.nch
.ods
.oft
.php
.pl
.sht
.shtm
.stm
.tbb
.txt
.uin
.wab
.wsh
.xls
.xml
.dhtml

The worm avoids email addresses that contain any of the following strings:


@example.
2003
2004
2005
2006
@hotmail
@msn
@microsoft
rating@
f-secur
news
update
.qmail
anyone@
bugs@
contract@
feste
gold-certs@
help@
info@
nobody@
noone@
0000
Mailer-Daemon@
@subscribe
kasp
admin
icrosoft
support
ntivi
unix
bsd
linux
listserv
certific
torvalds@
sopho
@foo
@iana
free-av
@messagelab
winzip
google
winrar
samples
spm111@
..
-0
.00
@.
---
abuse
panda
cafee
spam
pgp
@avp.
noreply
local
root@
postmaster@


Uses its own SMTP engine to send itself to the email addresses that it finds. The email has the following characteristics:

From: Spoofed.

Subject: [RANDOM]

Message: [RANDOM]

Attachment: [RANDOM]


Tries to contact the following Web sites and may attempt to download a remote file:


[http://]85.249.23.35/m2/g.p[REMOVED]
[http://]207.46.250.119/g/m.p[REMOVED]
[http://]84.22.161.192/s/f[REMOVED]


Opens a back door on a random TCP port.


RECOMMENDATIONS:


I encourage all users and administrators to adhere to the following basic security "best practices":

Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.


The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.


Disable System Restore (Windows Me/XP).
Update the virus definitions.
Run a full system scan.
Delete any values added to the registry.

For specific details on each of these steps, read the following instructions.

1. To disable System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.


Start your Symantec antivirus program and make sure that it is configured to scan all the files.
For Norton AntiVirus consumer products: Read the document: How to configure Norton AntiVirus to scan all files.
For Symantec AntiVirus Enterprise products: Read the document: How to verify that a Symantec Corporate antivirus product is set to scan all files.
Run a full system scan.
If any files are detected, follow the instructions displayed by your antivirus program.



Important: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.

Click Start > Run.
Type regedit
Click OK.

Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.


Navigate to the subkey:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Devices


In the right pane, delete the value:

"Application" = "[VARIABLE DWORD VALUE]"


Navigate to the subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe


In the right pane, delete the value:

"Debugger" = "[PATH TO WORM]"


Exit the Registry Editor.